The field of the present disclosure relates generally to molds for forming ceramic articles and, more specifically, to a thin-walled disposable core die.
At least some known turbine components, such as blades, nozzles, and vanes, have complex geometries. For example, turbine blades and nozzles may have internal passages and/or voids defined therein that must be manufactured in accordance with accurate dimensions having tight tolerances. In such instances, investment casting is generally effective at manufacturing parts that require precise dimensional accuracy.
When manufacturing turbine components as described above, investment casted parts may be formed and prototyped in a thermoplastic die before more durable steel dies are constructed. For example, thermoplastic dies, such as a disposable core die (DCD), may be formed from an organic polymer in a rapid prototyping process. Rapid prototyping involves forming an object, based on a digital model, by layering material with a 3D printing machine. Rapid prototyping is generally effective at forming articles that have complex internal structures and thin walls, such as a DCD. Further, investment casting includes injecting a low-viscosity, silica-based ceramic slurry into the DCD, and firing the ceramic slurry to form a solidified ceramic core.
When injecting the ceramic slurry into the DCD, the slurry must be injected at a pressure sufficient to fill the complex internal structures of the DCD. However, the complex internal geometry and thin walls of the DCD may result in problems arising when forming the ceramic core. For example, the thin walls of the DCD may be susceptible to rupture above certain injection pressures, and some portions of the DCD may have regions that are not filled by the slurry. Further, the gap distance defined between the walls of the DCD must be controlled, and portions of the core may shrink at different rates during slurry solidification. As such, there is a need for an improved thin-walled disposable core die for forming ceramic articles therein.